1. Field of the Invention
The present invention relates to a remaining toner detection apparatus that detects the amount of toner remaining in a toner cartridge of, for example, an electrographic or electrographic image forming apparatus and to an image forming apparatus provided with the same.
2. Description of the Related Art
Commonly known examples of electrographic or electrostatic image forming apparatuses include copying machines, printers, fax machines and the like. In such image forming apparatuses, an electrostatic latent image is formed on a photosensitive base and toner is supplied from a development apparatus to form a toner image on the photosensitive base, after which the electrostatic latent image is developed on the photosensitive base with toner. Thereafter, the toner image is transferred from the photosensitive base to a sheet of recording paper, and the toner image is fixed to the sheet of recording paper by applying heat and pressure to the sheet of recording paper.
Since toner is consumed in such image forming apparatuses, it is necessary to replenish toner. For example, a hopper is installed on the development apparatus and the toner cartridge is detachably fitted onto the hopper so that toner can be made to drop from the toner cartridge to the hopper, after which toner is supplied from the hopper to the development apparatus.
Furthermore, the amount of toner remaining in the toner cartridge is detected and indication is given when there is little remaining toner suggesting that the toner cartridge be replaced, thereby preventing in advance any break in the supply of toner.
A technique by which the remaining toner of a toner cartridge is detected using a remaining toner sensor that is constituted by a light-emitting element and a light-receiving element is disclosed in JP H07-56431A for example. More specifically, a vertical recess is provided near the bottom of the toner cartridge and two pairs of light-emitting elements and light-receiving elements are arranged in opposition to each other sandwiching the vertical recess. Toner is present in the vertical recess when there is sufficient toner, and therefore the light of each light-emitting element is blocked by the toner such that the light is not received by the light-receiving elements. Furthermore, when the amount of toner reduces and there is no toner in the vertical recess, the light-receiving elements receive the light from the light-emitting elements. Consequently, the output levels of the light-receiving elements are different when there is toner and when there is no toner, and it is possible to determine that there is no remaining toner based on the output levels of the light-receiving elements.
Furthermore, an elastic member is attached here to an agitator shaft that agitates the toner in the toner cartridge, and the elastic member is made to pass through the vertical recess by the rotation of the agitator shaft, so that the light irradiation surfaces of the light-emitting elements and the incident light surfaces of the light-receiving elements are cleaned by the elastic member.
However, with the apparatus disclosed in JP H07-56431A, even though the elastic member passes through the vertical recess to clean the light irradiation surfaces of the light-emitting elements and the incident light surfaces of the light-receiving elements, the light-emitting elements and the incident light surfaces of the light-receiving elements are always smeared since toner drops from above into the vertical recess immediately after this, and thus errors are made in determining the amount of remaining toner.
Furthermore, when there is little remaining toner, a repetitive action occurs by which toner is agitated and made to spatter up and then fall into the vertical recess, and therefore the toner level is not consistent and irregularity occurs in determining the amount of remaining toner.
The present invention has been devised in consideration of the conventional problems described above, and it is an object thereof to provide a remaining toner detection apparatus that can always accurately determine the amount of remaining toner and an image forming apparatus with the same.